Gonadotropin-releasing hormone agonist triggering of oocyte maturation in assisted reproductive technology cycles

Discovery of new receptors regulating luteinizing hormone and follicle-stimulating hormone secretion by bovine gonadotrophs to explore a new paradigm for mechanisms regulating reproduction

Previous studies in the 1960s and 1970s have reported that both gonadotropin-releasing hormone (GnRH) and estradiol-activated nuclear estrogen receptors regulate gonadotropin secretion in women. However, I had previously reported that gonadotroph function is regulated by complex crosstalk between several membrane receptors. RNA-seq had previously revealed 259 different receptor genes expressed in the anterior pituitary of heifers. However, the biological roles of most of these receptors remain unknown. I identified four new receptors of interest: G protein-coupled receptor 30 (GPR30), anti-Mullerian hormone (AMH) receptor type 2 (AMHR2), and G protein-coupled receptors 61 and 153 (GPR61 and GPR153). GPR30 rapidly (within a few minutes) mediates picomolar, but not nanomolar, levels of estradiol to suppress GnRH-induced luteinizing hormone (LH) secretion from bovine gonadotrophs, without decreasing mRNA expressions of the LHα, LHβ, or follicle-stimulating hormone (FSH) β subunits. GPR30 is activated by other endogenous estrogens, estrone and estriol. Moreover, GPR30 activation by zearalenone, a nonsteroidal mycoestrogen, suppresses LH secretion. AMHR2, activated by AMH, stimulates LH and FSH secretion, thus regulating gonadotrophs, where other TGF-β family members, including inhibin and activin, potentially affect FSH secretion. I also show that GPR61, activated by its ligand (recently discovered) significantly alters LH and FSH secretion. GPR61, GPR153, and AMHR2 co-localize with the GnRH receptor in unevenly dispersed areas of the bovine gonadotroph cell surface, probably lipid rafts. The findings summarized in this review reveal a new paradigm regarding the mechanisms regulating reproduction via novel receptors expressed on bovine gonadotrophs.

Empty Follicle Syndrome Following GnRHa Trigger in PCOS Patients Undergoing IVF Cycles

BACKGROUND

The objective of this study was to analyze the incidence and the underlying mechanisms of empty follicle syndrome (EFS) occurring in gonadotropin releasing hormone agonist (GnRHa) triggered in in vitro fertilization (IVF) cycles with GnRH antagonist protocol in women with polycystic ovary syndrome (PCOS) of Indian origin. The study also intended to evaluate the cycle outcome following a rescue trigger.

METHODS

Retrospective cohort analysis of data was extracted from the hospital database of 271 PCOS patients who underwent IVF in antagonist protocol triggered with GnRHa from August 2014 to December 2016. All cases with failure to obtain oocytes following retrieval were analyzed. Continuous variables were expressed as mean±SD using t-test and Chi-squared test for categorical variables. A p<0.05 was considered statistically significant.

RESULTS

Incidence of EFS following GnRHa trigger was found to be 3.3%. False empty follicle syndrome (FEFS) accounted for majority of the cases (8/9=88.8%). Of the nine EFS, six cases were salvaged with a rescue trigger, resulted in transfer of reasonably good quality embryos in a frozen-thawed embryo replacement cycle achieving clinical pregnancy in three cases (3/6=50%).

CONCLUSION

Our experience with EFS cases following GnRHa, albeit small, given the rarity of its occurrence, suggests that majority of EFS are of false forms and can be effectively salvaged which results in reasonably favorable outcome.